Micrometer caliper



May 18? 1937. P 1 DARUNGTON 2,080,534 l MIGROMETER CALIPER Original Filed Aug. 27. 1931 ,3 am "a 4 '42022 f' \/f t* @Z9/@Efe 2f .4943 INVENToR.

@ ATTORNEY.

Patented May 18, 1937 UNITED STATES fP TfE-N T OFF IC E MCROMETER CALIPER Application August 27, 1931, Serial No."559,708 Renewed January 6,1937

Claims.

This invention relates to micrometer calipers and with regard to certain more specific. features thereof, to high precision caliper gages.

The invention has for one of its objects to pro- 5 vide a sturdy and reliably operativegage7 which shall be serviceable in various uses, quickly adjustable to accommodate different sizes of work over a substantial range, and adapted to indicate readings of extremely high precision. Other objects will be in part obvious and in part pointed out particularly in the description which follows of one preferred form of the invention. By the use ofthe gage-hereinafter described there is an assured and maintained precision of diameter'to plus or minus one-half of one ten-thousandth of an inch.

This extremely high precision in gaging isobtained by the combined action of a number of features of construction which Vreduce'the errors of high multiplication gearing and substantially eliminate the personal factor of error. The dial indicator may be clearly read in ten-thousandths of an inch, and the effect of whipping ofthe indicator hand is neutralized. The inventionV permits the use of a low geared indicator with a dial reading in the above-mentioned high fractions, the amplication of movement between the caliper anvil and the indicator hand being effected in large part by leverage in the frame, which, coupled with a construction of anvil relationship and center-stop for the work causing each gaging operation to be ended by a controlled minus movement to zero, results in quickly obtaining accurate readings to the degree of precision stated.

The invention accordingly consists in the vario-us features of construction, combinations of elements and arrangements of parts which will be exemplified by the following description and the drawing and the sco-pe of the application of which will be indicated by the appended claims.

In the drawing:

Figure 1 is a view in perspective of the improved gage.

45 Figure 2 is a view in vertical cross-section of the gage shown in Figure 1.

Figure 3 is a top plan view of the gage shown in Figures 1 and 2 with parts broken away to show more clearly the clamping means for one of the 50 anvils with the indicator removed and certain parts in section. Figures 4, 5 and 6 are fragmentary views showing a modified form of contacting mechanism particularly adapted to the gaging of screw- Y 5 `threaded shafts or Shanks.

CTI

.spring 32. connected to the lever arm'2l at 33 and Referring now more particularly to the drawing there is-indicated at I0 a one piece main frame casting comprising side plates or wallsII and l2 integral with a spacing web I3. The sidewalls of the frameareprovided respectively with op. 5 posed slots iI4 and I'5 for the reception of parts ,of a quick adjustable Contact element I6. Ihe spacing web I3 Lis continued forwardly at its lower region :to .provide a boss II to which is secured a stop member I8Lfor purposes which 10 will presentlyappear. Between the side Walls I I and I2 aA lever I9 is pivoted at'i20. This lever is of the bell-crank typehaving alower substantially horizontal arm 2| and an upstanding arm `22. The-lower arm at its free end carries the 15 lower Contact `23` of the gage. The upstanding Varm rv22 is-provided at its free end with a cam plate fZIIeXtending forwardly of the arm. rIhe plate isl provided with a cam face 25 which bears against ya pin 26 of a lever arm 21, also pivoted 20 'between/the side walls ofthe frame at 28. The

lever arm 2'I is normally urged rearwardly, contacting the pin 26 with the cam face 25, by means ofthe usual spring plunger 29 of a standard make of dial indicatorrepresented at 30 as pivotally mounted between the frame walls on apin'3 I.

Thepivoted bell crank lever 'I9 carrying the lower caliperl contact 23 is normally held against thestop I8 on'the frame by a coiled retractile connected at its upper end to across bar 34 attached to the upper part of the frame. This holds the lever arm"2I normally and yieldably in substantially a right angle position with respect to the forward vertical edge 35 ofthe frame.

.A supplemental frame part '36 is formed of sheet metal curved .to present opposed edges 31 and 38 to the exterior of the frame walls II and I2 at their rear edges where the supplemental 40 frame is secured by screws or other fastening means 39. The upper region of the supplemental frame is shaped to provide spaced Walls '49 .and

v4I between which an operating handle 42 is pivinner side of the handle 42, but normally slightly spaced from the arm by means of a leaf spring 45 acting against a stop pin 45".

i The upper caliper contact element I6 is a quick adjustable device comprising a fiat anvil or contact member 46 secured to an adjustable arm 41 which has a spline 48 adapted to project between the spaced walls of the frame at the forward machined edge thereof. A bolt 49 has its shank 50 rotatively mounted in a section 5I of the arm 41. The flatted head 52 of the bolt is entered in the opposed slots I4 and I5 of the frame with some clearance for assembly purposes but without capacity for complete rotation of the bolt head. The threaded shank of the bolt is entered into a threaded bushing 53 which in turn is enclosed by a split operating member 54 having an actuating finger piece 55. The bushing' and operating member are associated to rotate in unison by tightening a screw-5ii bringing the split band of the operating member tightly around the bushing; The varm 41 is recessed at 51 to receive the operating member and bushing. As the actuating nger piece is moved, rotating the operating member and interior-ly threaded bushing, the threaded shank 50 of bolt 49 is axially moved due to its incapacity to rotate beyond narrow limits. This binds or loosens the arm 41 with respect' to the frame accordingly as the finger piece is moved in one direction or the other. It is intended that the device when in clamped position should have the finger piece moved to a home position against the arm 41 as shown in Figures l, 2 and 3. To loosen the clamp the finger piece is rotated substantially 90 degrees, thereby rotating the interiorly threaded bushing and urging the bolt rearwardly. To vary the clamping pressure the screw 56 is let off slightly, allowing for relative rotation of the bushing 53 and the split operating member 54. After such rotation the screw is again tightened so that the parts kmove in unison.

The gage may if desired be applied to the work as it is in production on a machine tool as in grinding it may be vused right rin front of the Wheel while grinding is in progress. It will be noted that the frame and projecting `anvils are of slight thickness, and in line with preserving the advantages of this construction is the idea of having the finger piece 55 movedliome against the arm 41 when the caliper member I6 is clamped to the frame.

A center-stopi is provided with a spring clip BI attached to a body 62. The latter is adapted to beary against the forward machined edges of the frame in the same manner as the arm 41 of caliper contact element I6. A'lower projecting end 63 ofthe clip 5 I `is provided with a slight cam face 64 which engages a rear surface of the stop member I8. An upper projecting end 65 of the clip 6I has a slight cam face 65 which is engaged by a machined rear surface of the quick-adjustable upper caliper contact element I6. As the latter is locked in adjusted position the center-stop with its projecting lug 51 is firmly held in its location. The described center-stop is typical of a plurality of pieces having bodies of various lengths which may be furnished as a part of the device or equipment. As. the upper contact elementholds the center-stop the latter serves to locate the position of the upper caliper contact.A The proper length of center-stop body is selected with a view to the rough size of the work to be gaged.

`When the center-stop has been inserted and the upper contact clamped the instrument is in condition for operation by the handle and hand grip. Pivotal movement of the handle by pressure reacts upon the lever arm 22 of lever I9 urging the arm 22 forwardly and dropping the lower contact 23 on arm 2l. The lever arm 21 is also moved forwardly in ratio.

The contacts or anvils 23 vand 4S are slightly converged toward their outer ends to obviate the effects of lost motion or backlash in the mechanism as later herein described. The jaws are applied over a master of the size to which the work is to be reduced and the dial indicator is set to zero in the usual way. Subsequently, as the gage is applied to the Work all movements of the pivoted lower Contact are transmitted to the dial indicator through the compound lever mechanism comprising the lever I9, the cam 24, pin 26 and lever arm 21. A screw 1U in the split upper end of lever arm 21 offers opportunity for adjustment at this point and bears against the standard Yspring plunger 29 of the dial indicator.r

By the described arrangement of anvils,r replaceable center-stops, leverage and dial indicator, any application of the gage to the workresults in the last movement of all the mechanism being in a minus direction controlled by the anvils as they contact the work and the gage is moved onto the work to bring the center-stop against the circumference. Duringthis movement the slight inward divergence of the anvils vallows the dial indicator plunger to react against its immediate lever, which in turn reacts against the elbow lever which is already in motion byiits spring. The operation, therefore, is one of primarily overrunning zero on the dial and then allowing the dial indicator to determine its own reading bythe action of its spring plunger against a leverage system which is stopped in motionwhen the center-stop abuts the surface of the work. The application of movement by the levers employed is, of course, present in this direction of movement, permitting a relatively large plunger movement for a very small closing-in movement of the anvils.

In the embodiment shown, the dial index finger of the indicator has its movement amplified to three times normal movement by the compound leverage mechanism described. 'This magnies any deviation from standard and results in gaging of the highest precision.

The importance of the slightly outwardly converging anvils combined with the amplifying mechanism should be particularly noted. vA1- though the convergenceis so slight as not to be distinguishable in the drawing, such as a thousandth of an inch or less, the motion ofthe lower anvil is amplified all the way to the tip of the indicator pointer in a series of stages. There is mechanical contact between each stage and the next under the pressure of one or more springs. There is friction at pivots and bearings. There is momentum in the rapidly moving parts when the opening grip is squeezed to apply the gage to the work or to the reference standard. After such action all these moving parts are liable to come to rest in slightly different positions with reference to each other, producing diierent readings on the dial with the same position of the lower anvil, or, in other words, producing inaccuracy of reading. When they come to rest, the last controlling influence may have caused some of them to fly apart, or, on the other hand, to squeeze together, or ksome of them to go one way and some the other. Under such conditions the feature of the converging anvils plays its .important part. `fluence which is always uniform. The gentle and It pro-videsfa nalcontrol inlof the operating.mechanism,may be the same as ,previously set forth. The center-stop `member may be used or itmay be eliminated, or a body may be used which has no lug. It is within the .scope of the invention to use a center-stop hav- `;ing a construction corresponding'to the upper and lower contact elements presently described. The lower armll of lever I9 is modified as shown clearlyiniFigure .4 of the drawing, to have attached thereto at the forward end a yoke 8B. 'Ihe quick-adjustable upper caliper I6 is modiiied to provide a yoke 8| at'its forward end. These yokes .are adapted to receive arbors 82 on which are rotatively mounted rollers83 and 84 with annular ribs or ridges 85 which enter the threads of the piece being gaged. The roller 83 .has a spacing portion 86 and the roller v8l has at its opposite end a spacingportion 81 whereby the ribs of the different rollers are arranged in staggered relation so as to properly enter the threads of the work piece at diametrically opposed points.

I claim:

1. A caliper instrument comprising a frame having a slideway, a caliper member arranged in said slideway for movement into different positions of adjustment, an opposed caliper member pivoted in said frame and yieldingly held toward the rst said caliper member, and a detachable center stop arranged in said frame intermediate the said caliper members and secured therein by adjusting the adjustable caliper member in the slideway toward the opposed caliper member and` securing it in adjusted position and adapted for removal when the adjustable caliper is unsecured and slid in the opposite direction.

2. A caliper instrument comprising a frame having a handle portion and a vertically slotted front, a stop member at said front, a lower caliper member pivoted in said frame, a spring normally holding said lower caliper member against the lower side of said stop, an upper caliper member arranged in the slotted front of the frame for sliding adjustment therein, means for securing the upper caliper member in different positions of adjustment relative to said stop, an indicator on the frame, means for transmitting movement of said lower caliper to saidindicator, and a detachable center stop arranged in said slotted front and having downwardly and upwardly projecting spring clip means adapted to engage respectively a rear face of said stop member and a rear face of the upper caliper member when the latter is adjusted downwardly.

3. Apparatus for calipering cylindrical work, comprising a frame, a lower caliper member pivotally mounted in said frame, an indicator on said frame, means for transmitting movement from said lower caliper to said indicator, an upper caliper member slidably vertically adjustable in the front of said frame, means for securing said upper caliper member in different positions of vertical adjustment, and a center stop detachably arranged, so as to be replaced by a center `stopof adiii'erentlengthgin the front of said iframev below said upper ycaliper and having means engageable .by thezupper caliper'member in its downwardly adjustable movement and releasable by movement of the upper caliper member in bounds 'anlopening through the frame, yan indicator having alportion extending between the side Walls at theftop ofthe frame vand supported therein, said'indicator having a spring pressed plunger, yan elbowlever pivotally mounted in the framebetween the sidewalls, a second lever d pivotally mounted infthe frame between the side walls in position to. be acted upon by'an arm of saidfelbow lever .andhaving a free end bearing againstftheiindicator plunger, a spring normally urging said elbowlever in a direction away from` i" said second le'ver, opposed guides on the inner sides of the frame walls at the front of the frame, a caliper member slidably arranged inthe guides, means for quick-releasably securing said caliper member inrdiferent positions along the guidesjv' and means for moving the elbow lever in opposition to its spring; said elbow lever having one end constituting-,a caliper element opposed to the first said caliper element.

5. A caliper instrument having a one piece*r body frame. comprising a transverse web dening a substantially central opening and side walls providing a channel around said web, a pivoted elbow lever and amplifying gearing arranged in said channel, said elbow lever having a caliper member at one end and a spring controlling its normal position, an indicator at the top of the frame associated for transmission of movement with said amplifying gearing, a slideway in the frame at the front, a center stop at the front of the frame, a caliper member arranged for sliding adjustment in said slideway, means for securing the latter said caliper member in adjusted position against said center stop, and hand grip means located at the rear of the saidv body frame having an actuating member normally spring held out of engagement with said elbow lever but adapted to be advanced upon it to move the same about its pivot. Y

6. A caliper instrument comprising a frame, a caliper member arranged for sliding adjustment in the front of said frame and means for securing said caliper member in an adjusted position and unsecuring said member when desired, comprising a bolt having a head portion shaped to be slidable but non-rotatable in said frame, a shank portion arranged in the caliper member and a threaded portion extending into an opening therein, a bushing in said opening threaded onto the extended threaded portion of the shank and held against lengthwise movement thereon by opposed faces of the caliber member, and a member extending outside of said frame for rotating said bushing to lessen or increase the longitudinal distance between said head portion and said bushing to thereby clamp or unclamp the caliper member in relation to the frame.

7. In a caliper, a frame, an elbow lever pivoted thereon having at one end an anvil, another anvil diametrically opposed to the rst said anvil and adapted to be secured in different adjusted positions on said frame, a center stop arranged circumferentially between said anvils, spring means urging the elbow lever toward a stop position, a

second lever pivoted on said frame adapted to be acted upon by the other end of the elbow lever, and a dial indicator of spring pressed plunger type mounted on said frame to present the plunger to the outer end of said second lever, the said anvils having a normal setting with their opposed faces converging toward their outer ends.

8. In a caliper, a frame, an elbow lever pivoted thereon having at one end an anvil, another anvil diametrically opposed to the iirst said anvil and adapted to be secured in different adjusted positions on said frame, a center stop'arranged circumferentially between said anvils, spring means urging the elbow lever toward a stop position, a second lever pivoted on said frame adapted to be acted upon by the other end of the elbowlever, and a dial indicator of spring pressed plunger type mounted on said frame to present the plunger to the outer` end of said second lever, the said anvils having a normal setting with their opposed faces converging toward their outer ends and said center stop being removable for replacement byanother of different size.

9. In a caliper, a frame, an elbow lever pivoted thereon having at one end an anvil, anotherV anvil diametrically opposed to the rst said anvil and adapted to be secured in different adjusted positions on said frame, a center stop arranged ciroumferentially between said anvils, spring means urging the elbow lever toward a stoprposition, a

second lever pivoted on said frame adapted to be y vits replacement by a center stop of different size.

l0. In a caliper, a frame, an elbow lever pivoted thereon having at one end an anvil, another anvil diametrically opposed to the first said anvil and adapted to'be secured in diierent adjusted posif tions on said frame, a center stop arranged circumferentially between said anvils, spring means` urging the elbow lever toward a stop position, a second lever pivoted on said frame adapted to-be acted upon by the other end ofthe elbow lever, a

dial indicator of spring pressed plunger type mounted on said frame to present the plunger to the outer end of said second lever, the said anvils having a normal setting with their opposed faces converging toward their outer ends, and a supplemental frame forming with a part of the main frame a hand grip and having av movable handv operable part normally spring-pressed out of engagement with the elbow lever adapted to be moved to engage same and move it in opposition to its spring.

PHILIP J. DARLINGTON. 

